Operations in mining and tunnel construction, some industrial branches, the military as well as fire-fighting or rescue missions in areas contaminated by natural disasters or accidents present considerable hazards to the respective workers. Such hazards can be toxic and/or explosive gases, hazardous radiation or high temperatures. Rescue workers are equally exposed to hazards created by falling objects and exposure to other physical impacts or extreme physical strain. In addition, the time people can work when breathing from a compressed air breathing apparatus is limited to the capacity of the compressed air bottle and must not be exceeded.
Various interconnected electronic warning, monitoring, control and information devices (hereinafter called ‘units’ for short) are required to monitor operating conditions, gather site information, check vital functions, determine the position and alert the respective person in hazardous or even life-threatening conditions or to control and monitor specific apparatuses such as a pressure reducer connected to a compressed air breathing apparatus or an oxygen system. For example, a monitoring and warning system consisting of the following units is provided for fire fighters wearing compressed air breathing apparatuses:                a monitoring device (ICU) for the compressed air breathing apparatus mainly containing pressure, motion, and temperature sensors, alarm and data displays (LED and LCD) as well as acoustic alarms;        a gas warning device for toxic and/or explosive gases        a positioning device (such as GPS)        a pressure gauge for measuring and monitoring compressed air bottles        control devices for the pressure reducer and the oxygen system        a measuring instrument for monitoring vital functions, and        a camera/thermal imaging camera information system.        
A telemetric module is another important unit of the system that is used to transmit system status and individual unit data to the base stations outside the immediate operating area to allow outside control over the people in the operating area. In addition, commands, information and messages from the base station are to be forwarded from the base station to the respective person via specific units.
Such complex electronic safety systems have considerable requirements regarding communication among the units and with the telemetric module as well as incorporating new components. Furthermore, compliance with applicable national or regional standards/regulations is required. Expensive additional measures have to be taken for an explosion-protected and trouble-free design and for integrating each unit.
It is therefore the problem of the invention to design a monitoring and warning system equipped with a telemetric module for bidirectional communication with a base station in such a way that simple and fail-safe connection setup, easy integration of additional units, and fast data transfer among system components and to the base station are ensured.